Here, in Austin, Texas, 53-year-old Joe Stack made a missile of his small plane, slamming it into an IRS office, a final expression of a simmering rage.

BOUDREAU (on camera): On the surface, Joe Stack seemed like a good guy - sound and perfectly sane. So what led this Regular Joe to become what some would call a domestic terrorist? What drove him to kill on February 18th?

BOUDREAU (voice-over): Rick Furley was a band mate of Joe Stack. Stack played bass, and was the kind of guy you could count on.

FURLEY: Super professional. Always on time, always knew the bars.

BILLY ELI, FRONTMAN, BILLY ELI BAND: Three, four -

BOUDREAU: Billy Eli was the front man who brought Stack into the band. He says the Joe Stack who flew his plane into a building was not the same Joe Stack he knew.

BOUDREAU (on camera): Some people call him a domestic terrorist.

ELI: Well, some people do, and some people call him all kind of things, man. I called him a friend of mine and my bass player, you know? I mean, I wasn't aware of any political agenda that he ever had.

BOUDREAU (voice-over): Austin's a town known for big Texas hospitality, vibrant music, and a thriving technology community. Joe Stack came here to start over.

Back in the '80s, Stack founded a small company in California and connected with a group of people obsessed with taking on the U.S. tax code. For Joe Stack, this was the beginning of decades struggling with the tax system.

J.J. MacNab is an expert on tax protesters.

J.J. MACNAB, INDEPENDENT PLANNER AND ANALYST: Their beef is somewhat varied, but in general they don't want to pay taxes and they come up with a variety of reasons how not to do that.

BOUDREAU: When Stack's marriage and business went bust in California, he moved to Austin. Here, he founded a software company, joined a band and got remarried.

On the outside, Stack seemed happy. But, beneath the surface, his life was far from it.

LISA ALEXANDER, IRS REVENUE OFFICER: There's all kind of people in the world and anything can happen any given day and anywhere.

Oh, OK.

BOUDREAU: Each day, after breakfast with her son -

ALEXANDER: All right.

BOUDREAU: Lisa Alexander heads to work. February 18th was no different.

This single mom is a revenue officer for the IRS in Austin.

ALEXANDER: I tell the taxpayer we're out here to assist you, to work with you, with your delinquency with the Internal Revenue Service, because we know the economy is hurting but we still have a job to do.

BOUDREAU: That morning, Alexander settled into her routine here at the IRS offices.

ALEXANDER: Checked my mailbox and pranced around the office, and then I finally get situated.

BOUDREAU: Across town, it was also business as usual for glass repairer Robin DeHaven. He had already started his workday.

ROBIN DEHAVEN, GLASS REPAIRER: I was already at work. I'd already picked up my workload and I was just trying to go through my - my workload. I had a - a few tickets, windows to look at, doors to look at or windows to repair.

BOUDREAU: The Iraqi War vet headed out to his first job.

DEHAVEN: It was a nice pretty much day, clear. The traffic wasn't too bad at that point.

BOUDREAU: February 18th - for most people, just an ordinary day. But for Joe Stack, he'd reached his breaking point. Trouble at home, finances running low, and an audit by the IRS.

That morning, Stack finalized his 3,000-word manifesto. UNIDENTIFIED MALE: If you're reading this, you're no doubt asking yourself, why did this have to happen? The simple truth is that it is complicated and has been coming for a long time.

BOUDREAU: Stack had been writing for months. He railed against the government.

UNIDENTIFIED MALE: The monsters are the very ones making and enforcing the laws.

BOUDREAU: And he foreshadowed his fatal plans.

UNIDENTIFIED MALE: Violence not only is the answer, it is the only answer.

BOUDREAU: Less than an hour later, as Lisa Alexander reviewed cases at the IRS, as Robin DeHaven headed down the highway, Joe Stack was taking off on a deadly mission.

(END VIDEOTAPE)

(COMMERCIAL BREAK)

(BEGIN VIDEOTAPE)

BOUDREAU (voice-over): The Giddy Up Bar, Austin, Texas, a typical Saturday night for Billy Eli and his band.

ELI: Joe Stack was a bass player in my band for about two years and he was a good musician. He was a conscientious musician.

BOUDREAU: Joe Stack played with Billy Eli's band in the honky tonks and hole in the wall beer joints dotting Central Texas. He was the band member everyone could count on.

ELI: He was a meticulous kind of engineer head kind of guy, you know? He loved - man, he loved things that you could do by the numbers. He had a good sense of humor.

BOUDREAU (on camera): Was he ever angry? Was he depressed?

ELI: You know, I never saw him angry.

BOUDREAU (voice-over): Band mate and drummer Rick Furley also remembered Stack as a laid-back kind of guy.

FURLEY: It's you want to sit down and have a beer with the guy. We never saw him angry. We never saw him get flustered. He was always in a good mood.

BOUDREAU: During all the gigs the band played together, Stack never hinted at his problems with the IRS.

ELI: I can honestly say the IRS never, ever came up in any conversation that we had. But, you know, I mean, we were - we were musicians and - and friends, and we talked about music. BOUDREAU: Stack helped with the band's album.

FURLEY: The last time I - I really had any interaction with Joe was at our - he was producing the album "Amped Out". He did a great job. He made it real easy and we were able to go in and - and record our tracks in fairly record time.

BOUDREAU: He also wrote a song for another band, Last Straw, called "A Certain Kind of Magic". He played keyboard, sang background, and even came up with the album title, named, ironically, "Over the Edge".

Music was also a big part of Stack's life growing up.

PHIL DAY, CLASSMATE: We were band mates, we were friends and also in Glee Club together. We toured and sang and so forth. So it was a - really a musical connection, I guess, between us.

BOUDREAU: Phil Day was the lead singer in the high school rock band called the Mythical Maze. Back then, Joe Stack was still playing bass. Growing up, Andrew Joseph Stack went by the name Andy.

DAY: I don't think he ever saw himself as a star. He didn't - it wasn't that type of personality. You - you know, you can kind of tell the people that would love to be out in the limelight and - and be a - a - headlining a show somewhere. That wasn't Andy.

BOUDREAU: The school they attended together was the Milton Hershey School, a residential school for orphans in Hershey, Pennsylvania.

When Stack was a young boy, his father died of a heart attack. After his sudden death, Andy's mother, Ethel, was unable to care for her two oldest sons, Andy and Harry, so she enrolled them in the Milton Hershey School in 1963. Andy was just 7.

Then, another tragedy, Andy's mother died months later. It was suicide. Harry Stack told "The Austin American Statesman" she killed herself with a gun.

While his other siblings moved in with relatives, Andy and Harry stayed at Milton Hershey, where they became what classmates called lifers.

DAY: Some kids came in at kindergarten and went through the entire - until high school graduation, and those were the lifers.

BOUDREAU: Hershey classmate Michael Macchioni remembers the hardscrabble life of his fellow classmates.

MICHAEL MACCHIONI, CLASSMATE: We were desperately poor and we had tragedy in our lives. One or both parents were dead. Some of the parents, you know, were killed in serious accidents or murders or any type of the sundry ways of dying.

And, either way, it was tragedy because we were all young children.

BOUDREAU: Daily life at the school was regimented. Danny Caffer (ph) roomed with Andy during high school.

DANNY CAFFER (ph), CLASSMATE: We would get up about 5:45 every morning. We had chores to do and the house parents would inspect our daily chores, and we were on a merit system. You could get a demerit if your job wasn't done well.

MACCHIONI: Each of the homes would have their own dairy farm and we milked cows twice a day. And the only times we didn't milk the cows is when we were away on vacation.

BOUDREAU: Students were often teased when they ventured off campus.

DAY: I remember traveling to, you know, football games and so forth to other schools, and kids at other schools would taunt us because we were orphans.

We were at one school and we'd beat them pretty badly in - in the game and getting back onto the buses, there were a bunch of cheerleaders out there singing or chanting, we might have lost, but we're not sad, because we still have our mom and dad.

DAY: Even when I look back at photos of - of Andy and so forth, it didn't matter what was going on around him, it always looked like he was thinking about something else.

There was an intensity about him, always seemed to be in that world where you knew there was something happening, but he wouldn't vocalize what it was. You - you could sense maybe there was something bothering him, but he wasn't going to verbalize it, that it was just something he dealt with.

MACCHIONI: He had an acerbic wit for sure. But, to myself and others who weren't close friends with him, you would say he was shy and reserved, even.

However, his friends report that once you got to know him, he was actually pretty friendly.

BOUDREAU: When Stack graduated in 1974, the Milton Hershey School gave him what they gave all their graduating students.

CAFFER (ph): You were given a suitcase of clothes and $100. They kept $10 in case you had any outstanding phone calls or anything, and said, "See you."

BOUDREAU: But Stack struggled, finding his own way.

DAY: I think Andy struggled when he first came out of Milton Hershey and was trying to figure out what direction he wanted to go in. I think the first couple of years were really tough for him and then it took him a while to - to get on his feet after that, it seemed.

BOUDREAU: Stack attended Harrisburg Area Community College, but he struggled, barely making ends meet.

UNIDENTIFIED MALE: I was living on peanut butter and bread, or Ritz crackers when I could afford to splurge, for months at a time.

BOUDREAU: Stack would go on to find his future in California - a future that was far from bright.

UNIDENTIFIED MALE: My introduction to the real American nightmare starts back in the early '80s.

An icon of the democracy movement in Myanmar has been freed from house arrest. Aung San Suu Kyi walked out of her home a free woman today. The Nobel Peace Prize Laureate has been imprisoned or confined to her home by Myanmar's ruling military regime for 15 of the past 21 years. She's expected to speak to her supporters on Sunday.

Medical workers in Haiti are appalled at the number of patients dying and being hospitalized in the cholera outbreak. The U.N. says the death toll is at least 800 with more than 12,000 hospitalized. The leader of the Doctors Without Borders Program says his staff is now seeing seven times the number of patients they did three days ago.

A top county official in suburban Washington says he will be cleared of federal charges that he and his wife received years of kick backs from real estate deals. Jack Johnson is outgoing executive of Prince George County in Maryland. Leslie Johnson is a county councilwoman. Both appeared in federal court Friday after a four-year FBI investigation. Just as they were about to be arrested, agents allegedly heard the couple flushing a check for $100,000 down the toilet. A search also revealed Mrs. Johnson was allegedly hiding $800,000 in her bra.

She's one of Hollywood's original blonde bombshells. Actress Zsa Zsa Gabor went home today after an emergency trip to Los Angeles Hospital. Paramedics feared a massive blood clot in her leg could have traveled to her heart. It turned out to be an infection. Gabor is 93 years old.

Those are your headlines this hour. A CNN Special Investigation, DEATH AND TAXES continues right now.

(BEGIN VIDEOTAPE)

BOUDREAU (voice-over): In the early '80s, Joe Stack found himself in Southern California, a hot bed of the anti-tax movement.

ANDRE HENSLEY, UNIVERSAL LIFE CHURCH: There were several groups in the Southern California area who realized that, you know, once a minister became ordained and started their own church, there were certain tax benefits for them.

BOUDREAU: Andre Hensley is the president of the Universal Life Church, a church founded in 1959 by this man, Kirby Hensley. He was Andre's father.

HENSLEY: Our whole goal is to help people with the freedom of religion, and if they want to start their own church, we want to help them to do that.

BOUDREAU: J.J. MacNab is a tax expert who's writing a book on tax protester schemes.

MACNAB: My understanding is they have about 40,000 or 50,000 people set up home-based churches in which they said if you turn your home into a church, then you are tax-free.

BOUDREAU: And that's exactly what Joe Stack did. He began his own tax-exempt church.

UNIDENTIFIED MALE: Some friends introduced me to a group of people who were having tax code readings and discussions, in particular zeroed in on a section relating to the wonderful exemptions that make institutions like the vulgar, corrupt Catholic Church so incredibly wealthy.

BOUDREAU: MacNab speculate Stack must have thought he was actually doing something heroic.

MACNAB: That he was being somewhat like the Founding Fathers, that he was protesting and - just like they did, and that he would be a hero and that others would learn from his heroic efforts and - and move on.

BOUDREAU: Although the IRS revoked his tax-exempt status from 1978 to 1985, the Universal Life Church challenged that ruling and today says it never advocated tax evasion.

HENSLEY: If you have a tax due and you feel that you, you know, have earned money, then you need to pay your taxes. Work within the system. It's there. That's the bottom line.

BOUDREAU: But the bottom line for other tax protesters was to push the system as far as they could.

UNIDENTIFIED MALE: You know, in the late '70s and early '80s, all the way up probably through the middle '90s, there was quite a bit of tax protest going on in the country in terms of people raising issues and litigation and those sorts of things.

BOUDREAU: This man says he's been a tax protester for more than three decades. He doesn't want us to show his face because he's fearful of what he says could be retribution by the IRS.

UNIDENTIFIED MALE: Most people think in our society that you're innocent until proven guilty. But when it comes to tax issues, you're guilty until you can prove that the IRS is wrong.

BOUDREAU: And during that time, Stack, according to documents obtained by the "Associated Press", did not pay taxes for 1981, '82 and '83. In his manifesto published on the Internet, here's how he described part of his battle.

UNIDENTIFIED MALE: We carefully studied the law with the help of some of the best, high paid, experienced tax lawyers in the business, and then began to do exactly what the big boys were doing, except that we weren't stealing from our congregation or lying to the government about our massive profits in the name of God.

MACNAB: It's not the IRS that makes the large churches tax exempt. It's Congress. The IRS simply collects money. They don't write the rules, they don't - they don't pass the law.

BOUDREAU: That distinction apparently made little or no difference to Stack.

According to court documents, he filed suit against the IRS in the fall of 1983. Five years later, he lost. According to the "Associated Press", he had to pay back taxes of $14,446, plus interest and penalties.

Here's what he wrote.

UNIDENTIFIED MALE: That little lesson in patriotism cost me $40,000 plus 10 years of my life and set my retirement plans back to zero.

BRIAN LEVIN, CENTER FOR THE STUDY OF HATE & EXTREMISM: This wasn't something that came out of nowhere. He - he has for a long time regarded the tax system as unfair and causing him unique and debilitating personal losses.

BOUDREAU: Brian Levin is a criminologist who specializes in analyzing acts of so-called Lone Wolf Violence. He says Joe Stack was influenced by the anti-tax movement.

LEVIN: He was the prototypical lone wolf. The more they go off alone, the more that anger festers and they're able to get caught in a web of a belief system, which then - when coupled with this emotional instability becomes a volatile and dangerous mix, and it's most likely to be directed against a symbolic target that they believe is at the root of their setbacks and pain.

And this is - this is payback. It is not just political, it is personal.

BOUDREAU: Joe Stack would remain in California in the late 1990s, where he continued to run afoul of the IRS.

He formed two software companies, and records show he failed to file corporate taxes on either. He began to funnel his anger and frustration, targeting the IRS.

LEVIN: This was not someone who is just going to go and hurt somebody randomly or just go after any government official. This was someone who wanted to declare war on the IRS and to have a movement continue after he was gone to do it as well.

UNIDENTIFIED MALE: The neighbors are all very friendly and helpful people, just kind of middle America, I guess you would say.

BOUDREAU: Elbert Hutchins lived two houses down from Joe stack. Like other neighbors, he believed this was the last place a rampage would be born.

UNIDENTIFIED MALE: It's just incredible. You know, you would never suspect something like this.

BOUDREAU: IRS employee Lisa Alexander was just returning to her job after a few days of field work. She was looking forward to a good day.

LISA ALEXANDER, IRS EMPLOYEE: I didn't get any type of vibes or I didn't feel anything or nothing new, it was supposed to be an ordinary day.

BOUDREAU: Like Alexander, Robin Dehaven, an Iraqi war veteran was just going through his daily routine as a window installer.

ROBIN DEHAVEN, IRAQI WAR VETERAN: I was going to do a window repair, a pretty simple job I thought and I was going to try to contact this woman and go change a window out.

BOUDREAU: An unsuspecting hero, an unwitting victim and a suicidal killer, all three on a collision course. Joe stack had harbored a grudge against the IRS for years, but in the months leading up to February 18, he had taken to his computer to write his manifesto.

BRIAN LEVIN, CRIMINOLOGIST: Joe Stack was someone who felt that his concerns were not listened to and Joe Stack felt that the system was biased against him.

BOUDREAU: Stack's manifesto is a litany of grievances, a rant, but also a window into his thoughts as he spiralled downward.

UNIDENTIFIED MALE: I find the process of writing it frustrating, tedious and probably pointless, especially given my gross inability to gracefully articulate my thoughts in light of the storm raging in my head.

BOUDREAU: When he's done, Joe Stack signs, dates and posts his online script and then leaves his computer for good.

(on camera): This is the house Joe Stack shared with his wife and stepdaughter in North Austin. On the evening of February 17, his wife and stepdaughter fled to a hotel, after Stack reportedly went ballistic over his problems with the IRS. This is what happened the next day. Around 9:15 a.m., he set his house on fire.

(voice-over): Albert Hutchins was at home that morning.

ALBERT HUTCHINS: My wife was watching TV and we both heard a loud noise and we rushed out into the backyard to see what was going on and we saw smoke and flames coming from the second floor window of the Stark's house. And I ran back through the house and grabbed our cordless phone and ran to the front yard while I was dialling 911.

BOUDREAU: His manifesto posted, his house torched and Stack, he was now gone.

(on camera): After he set his house on fire, he got in his car and set out on his real mission. He drove 20 miles north to an airport where he kept a single engine plane.

(voice-over): This is where Stack would take his final ride. According to the NTSB, Stack was cleared for takeoff at 9:44 a.m. and looking back, his voice sounds eerily cool for a man who was about to do what he was about to do.

BOUDREAU (voice-over): My pilot on this day is Jerry White. He was also flying February 18th. Just ahead of Joe Stack.

(on camera): Do you remember that day, did it look similar to today?

JERRY WHITE: It was just like today, he was right behind me.

BOUDREAU: So you saw him take off.

WHITE: Yes, and he had a very normal takeoff.

BOUDREAU: Nothing out of the ordinary? WHITE: Nothing at all out of the ordinary. Just another guy up there.

BOUDREAU: At 9:54 a.m., Stack begins descending rapidly. He makes a turn to the west. Three minutes later, 9:57, he slipped off the radar.

(COMMERCIAL BREAK)

DON LEMON, CNN ANCHOR: I'm Don Lemon. Here are your headlines this hour everyone. An icon of the democracy movement in Myanmar has been freed from house arrest.

Aung San Suu Kyi walked out of her home today a free woman. The Nobel Peace Prize laureate has been imprisoned or confined to her home by Myanmar's ruling military regime for 15 of the past 21 years. She's expected to speak to her supporters on Sunday.

Medical workers in Haiti are appalled at the number of patients dying and being hospitalized in the ongoing cholera outbreak. The U.N. says the death toll is at least 800 with more than 12,000 hospitalized now.

The leader of Doctors Without Border says, his staff is now seeing seven times the number of patients than they did just three days ago.

A top county official in suburban Washington says he will be cleared of federal charges that he and his wife received years of kick backs from real estate deals.

Jack Johnson is outgoing executive of Prince Georgia's County in Maryland. Leslie Johnson is a city country councilwoman. Both appeared in federal court on Friday after a four-year FBI investigation.

Just as they were about to be arrested, agents allegedly heard the couple flushing a check for $100,000 down the toilet. A search also revealed Mrs. Johnson was allegedly hiding $80,000 in her bra.

E-mail and online bill paying are taking a big bite out of the U.S. Postal service. The agency says it lost $8.5 billion last year. That's more than twice the nearly $4 billion it lost last year. People just aren't buying as many stamps.

Those are your headlines this hour. I'm Don Lemon. The CNN investigation "Death and Taxes" continues right now.

UNIDENTIFIED MALE: I'm thinking it's going to be a normal day.

BOUDREAU (voice-over): Robin Dehaven was driving down the road on February 18th, like he is on this day with me. And that's when something he had never seen, caught his eye, something small, flying much too close to the ground.

DEHAVEN: I looked on the horizon and I just saw a little white dot and I didn't know what it was. I'm staring at it like why is this? I realized there was a plane, but it didn't look like a small plane. I thought why -- I have never seen toy planes flying around here. What's it doing?

BOUDREAU: But Dehaven would soon realize it wasn't a toy, it was a real plane, Joe Stack's Piper Cherokee.

DEHAVEN: It was coming in at an angle so it was acting erratically. I'm waiting to see is this going to keep going. I was going to see it fall out of sky - or what and then I saw him turn and I thought, well, there's no more waiting, here we go.

BOUDREAU: Lisa Alexander was just getting settled into her morning routine at the Echelon Building in North Austin. She remembers hearing the familiar sounds of her IRS colleague and friend Vernon Hunter walking into the office.

ALEXANDER: I remember Vernon coming through humming that morning. I didn't actually see Vernon. I just heard come through. Good morning, good morning that what's he usually does. He was making his morning stroll and then I finally get situated and, bomb.

UNIDENTIFIED MALE: A single engine aircraft has crashed into a seven- story building.

UNIDENTIFIED MALE: Within seconds I saw a big plume of black smoke so I knew it had crashed.

UNIDENTIFIED MALE: It was like a fireball, some people were crying.

UNIDENTIFIED MALE: Some people were running, some people were peeling out in their cars and we could see smoke pouring out of the building.

UNIDENTIFIED MALE: The pilot apparently crashed into the building intentionally.

BOUDREAU (on camera): Stack slammed his plane between the first and second floors of this building. It exploded on impact.

ALEXANDER: It's like the building kind of swayed.

BOUDREAU (voice-over): Lisa Alexander had no idea what had just happened. The impact was seismic.

ALEXANDER: It was like, I know we're not having an earthquake, and then the explosion, it's like, my God, and by that time the tiles start falling down and the windows start shattering and then it was dark.

BOUDREAU: Chaos quickly turned to fear as Alexander and others began to try to escape.

ALEXANDER: And as we open the door, this poof sound comes in as if there was a plane or something behind it. And that's when I said, my God, I'm not going to see my son.

BOUDREAU: Robin Dehaven headed for the smoke.

(on camera): So you just drove into this parking lot?

DEHAVEN: When I saw that this is where it was coming from, I just turned right away and flew into this avoiding the people that were running.

BOUDREAU (voice-over): A veteran of Iraq with two tours under his belt, Dehaven says his instinct kicked in. He grabbed his ladder and raced to help those trapped in the building, those like Lisa Alexander.

ALEXANDER: We get to the window and we're all yelling and screaming, help us, help us.

BOUDREAU: Dehaven tried to help, but he couldn't find solid footing for his ladder. At one point, the ladder was swaying, with no other choice. He climbed into the burning building.

DEHAVEN: There was just daylight through the broken windows in that room. Enough I could see there's office cubicles, chairs, looked like somebody just knocked stuff over, ceiling tiles were falling down.

BOUDREAU: Dehaven eventually made eye contact with Lisa Alexander and her reaction was unmistakable.

(on camera): He said that he looked into your eyes and he saw fear, panic.

ALEXANDER: Yes, because I didn't know if there was going to be another explosion or not, and I just knew if there was, that's one that's going to take us out.

BOUDREAU (voice-over): After the ladder was finally steadied, Dehaven had to talk Alexander out of the building to safety.

DEHAVEN: The look on her face when she started climbing up that ladder and she was in straight panic.

ALEXANDER: I was nervous so I was like shaking, and Robin is like, I got you, just come on, put your foot down, you can do it.

DEHAVEN: I was trying to be nice and say, ma'am, we got to do this, just trying to earn her trust.

ALEXANDER: That's not the way I wanted to go down, but that was the only way next to jumping. It feels good to be on this side.

BOUDREAU: Alexander remembers not only Dehaven's reassuring words, but also the encouragement of the crowd that had gathered after the attack.

ALEXANDER: I guess the crowd helped me out because I was real nervous.

BOUDREAU (on camera): People were cheering for you?

ALEXANDER: Yes, like you can do it, you can do it. BOUDREAU (voice-over): After Alexander, Robin Dehaven went back five more times into the smoldering building, helping rescue six lives in all. From the air, it's obvious that this attack could have been so much worse.

(on camera): You can see the damage from here.

WHITE: Yes.

BOUDREAU: Wow, that's so close to the freeway.

WHITE: It's right there.

BOUDREAU: This could have been a real disaster.

WHITE: Yes.

BOUDREAU (voice-over): Coming up, could there be another Joe Stacks out there? And how concerned should those who work to the federal government really be?

ALEXANDER: His story was about the IRS, but it became a reality that day for me, I don't know if this is what I want to continue to do.

(COMMERCIAL BREAK)

BOUDREAU (voice-over): One man, one plane and one deadly mission.

ALEXANDER: For that whole week I was waking up at between 1:00 and 2:00, just crying my eyes out, you know, glad to be here and puzzled as to why did I come so close to death?

BOUDREAU: Survivor Lisa Alexander's trauma is still fresh.

(on camera): When you finally found out that this person, it wasn't an accident, he targeted that building, he targeted you.

ALEXANDER: You hear stories about the IRS, but it became a reality that day for me. It was like I don't know if this is what I want to continue to do or not.

And as time progressed, it was, you know, a message from God to me saying, like, hey, if I took you to that and brought you through, when it's your time, you're going to go. Everybody else got out except for Vernon.

BOUDREAU (voice-over): Vernon Hunter, a close friend and colleague did not survive. The 68-year-old veteran served two tours in Vietnam.

ALEXANDER: Vern, he was a nice guy, he would do anything for you.

BOUDREAU: Hunter was a husband, a father, and a grandfather of seven.

KEN HUNTER, VERNON HUNTER'S SON: For my 5-year-old, I mean, she loves me just, the two of them together had so much fun. And, you know, he would talk about seeing her when she grows up or when she graduates from high school and college, he's not going to see that, she's going to miss all that time with him.

BOUDREAU: The Patriot Guards stood by and U.S. flags waved in honor of the veteran who served his country.

(on camera): What are you thinking?

ALEXANDER: I hate that happened and I question why and why did we come so close? And that it just ended up being Vernon.

BOUDREAU (voice-over): Lisa Alexander did find some meaning in the tragedy that day.

ALEXANDER: Because I have been raised all my life to go to church and believe in God. And it's like, you know, maybe it is time for me to start believing.

UNIDENTIFIED MALE: In memory of the tragic events last week --

BOUDREAU: One week after the tragedy, a moment of silence and a ceremony to honor emergency responders and Robin Dehaven for their service.

UNIDENTIFIED MALE: Robin Dehaven is a true hero.

DEHAVEN: We know that time is of the essence in a situation like that and someone needs to react right away that's willing to do it.

BOUDREAU: He was at the right place at the right time.

DEHAVEN: It was like no, no, go away the building is on fire.

BOUDREAU: Not surprising since Dehaven wanted to rescue people for a living.

DEHAVEN: I actually tried out for the Fire Department two years prior too and so it's just kind of like --

BOUDREAU (on camera): What happened there?

DEHAVEN: I didn't make it.

BOUDREAU: Big mistake.

DEHAVEN: Yes.

BOUDREAU (voice-over): He received the city's public service honor for being a hero, a title he's still getting used to.

(on camera): People call you a hero?

DEHAVEN: Yes, I'm like, OK -- like my son asked me the other day, you're a hero, aren't you, daddy? Just out of nowhere because he's heard that from his mom and grandma and grandpa and I said, yes, at one point I guess I was a hero. But I'm not a normal hero, I'm just your dad.

BOUDREAU (voice-over): The suicide attack that left 2 dead and 13 injured also left those who knew Joe Stack conflicted.

UNIDENTIFIED FEMALE: My heart grieves for the loss of life caused by my husband.

BOUDREAU: Stack's widow Sheryl has spoken little about the tragedy, but made this statement at a fund-raiser for her and her daughter.

UNIDENTIFIED FEMALE: I am the victim of a violent crime. Done by someone I loved and who loved me very much. I have a lot to come to terms with dealing with that.

BOUDREAU: Mourning the man they knew and loved, but feeling angry and betrayed by his actions. Friends like Billy Eli were also shocked that Stack was behind the suicide attack.

BOUDREAU (on camera): So then you realized it was your friend Joe Stack who flew his plane into the building?

ELI: Yes, and I started mentally shuffling all the cards and trying to figure out how this couldn't be right, how this couldn't be Joe. It's got to be something else. It's got to be more to it than I'm hearing.

BOUDREAU (voice-over): And that's what makes a lone wolf like Joe Stack so disturbing that he operated under the radar. According to an FBI report, the most significant domestic terrorism threat over the next five years will continue to be the lone wolf terrorist.

Inspired by the ideologies of former terrorism groups, their relative anonymity limits law enforcement detection capability and makes prevention extremely difficult. Brian Levin, an expert on lone wolf extremists echoes that warning.

LEVIN: When you take extreme hatred and emotional instability, and hook it in whole or even in part to a belief system, you set forth a walking time bomb.

BOUDREAU: Just as disturbing, Stack's friend Billy Eli has been contacted by extremists who expect him to take up Stack's cause.

(on camera): All of a sudden, you're linked to Joe Stack?

ELI: Right, I'm getting fallout from that. I've got people that are like, hey, I know you're going to want to pick up the gauntlet, and, man, there's no gauntlet.

LEVIN: He wanted to light the fuse that would cause a general up rising by others who feel cheated by the tax system to act out violently as well. BOUDREAU: And he cautions, there may be other Joe Stacks out there.

LEVIN: He's become a folk hero to some in the anti-tax world. The extreme anti-tax world, that is and that's not only sad, it's dangerous.

And I'm not talking about conservative people with good will who go to church and vote for conservative candidates. I'm talking about people who are opted out and when one person opts out and commits violence, there will be others who invariably are influenced by that. And what I worry about is the next Joe Stack will be more successful.